Holt McCallany would like to tell a story about Ed Kemper. The cops that the friendly-seeming homicidal maniac talked shop with at his local watering hole usually called him "Big Ed"; after he was convicted of murdering six young women in Santa Cruz, California, he earned the name "The Co-ed Killer." This particular Kemper tale has the bulky, 6-foot-1 actor up on his feet, moving around the room in the most animated way imaginable; Jonathan Groff, his acting partner-in-crime – and cohort in based-on-a-true-story TV-show criminal profiling – watches quietly, his eyes continually moving between his Mindhunter costar and the journalist positioned between them.

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"He liked to pick up hitchhikers," McCallany recounts, pacing. "Kemper had his car set up so that once one of his victims got inside, she couldn't get out. Can't open the passenger door, can't roll down the windows – a prison on wheels. And he used to keep his various implements of torture in the trunk. So Ed picks up this young Korean woman. He gets out to go to the trunk, to get his 'tools' ... and he accidentally locks himself out of his own car. He spends the next few minutes sweet-talking the girl, saying, 'Let me back in. Come on, you don't need to be scared of me. But you do need to open the door, please. Just open the door.'" The actor's voice has taken on a sweet, almost lilting tone as he pleads with the female inside the vehicle. "And then, eventually, she does. He convinces her to open the door. Ed seems so nice. And he kills her. Viciously."

A few minutes later, after excitedly re-enacting John Wayne Gacy's pre-murder snake charming act ("We'll have some fun, we'll have some drinks ... hey, you like magic tricks? These are handcuffs. Put 'em on! Go ahead, it''ll be fun, I'll show you a trick ..."), McCallany calmly takes his seat again. "It's the mundanity as well as the depravity that makes the difference," he says, referring to the hold that serial killers have on the public imagination. "It's the unfathomable nature of the crimes that both fascinates and horrifies." The "how" can be parsed in endless Wikipedia entries – it's the "why" behind the pathology that maintains the interest.

The actor looks across the table at Groff, who silently nods. Then both of them lean forward and fix their gaze on the person holding the tape recorder. If anybody were to walk by, they'd think these two men were interrogating a suspect.

Both a refinement and a refutation of the standard pop-cultural narrative behind cops and/or Feds-vs-serial-killer thrillers, Mindhunter – Joe Penhall and David Fincher's new 10-episode series that begins streaming on Netflix today – takes viewers back to the spirit-of-'77, ground-zero moment of the Bureau's criminal profiling unit. Based on former agent John E. Douglas's 1995 book, the show follows hostage negotiator Holden Ford (Groff) as he's summoned to Quantico, Virginia. Teamed up with veteran agent Bill Tench (McCallany), the eager-beaver "blueflamer" and his older partner are assigned to hit the road and lecture on law-and-order techniques; Ford, however, is more intrigued by finding out what makes a murderer's mind tick. After some illuminating jailhouse interviews with "Big Ed" Kemper (Cameron Britton), the two men convince their superior to let them devote their energies to this pursuit full-time. "How can we get ahead of crazy," Tench asks near the end of the second episode, "if we don't know how crazy thinks?"

The result is part Me Decade period piece, part procedural and pure Fincher-esque stylistic horrorshow, as the duo compile data files on the era's most notorious "sequence" killers – Kemper is not the only real-life monster who puts in an appearance – and everything is filmed in various degrees of pitch black, rancid green and numerous shades of gray. (Though he's officially an executive producer, Fincher also directed close to half the episodes.) But while the filmmaker has a long history with the subgenre, the touchstone here isn't his influential thriller Seven so much as his 2007 masterpiece Zodiac, in which gents in off-the-rack Seventies suits pound the pavement and long scenes of people talking keep a constant sense of dread on simmer.

"Oh, I love interrogations!" Fincher admits, calling in from Los Angeles. "I love scenes where someone is resisting the temptation to reveal things. An eight-page scene with four walls of containment fences and a stainless-steel picnic table? I'm there. Filmmakers go, 'Ah shit, this is going to be so boring. I need to shoot some flashbacks.' But I always go back to Jaws. It's a lot more interesting in my mind to listen to Robert Shaw tell the story of the USS Indianapolis than to just cut to 1,100 men being eaten by a thousand sharks.

"You can make that scene as huge as you wanna make it," he adds. "But his reminiscence of Herbie Robinson from Cleveland is what's forever seared in your memory after you watch that film. That's exactly what we were going for here. And it had to be a TV show."

In fact, when Fincher was first given a book about the history of the Bureau's profiling unit – not Douglas's tome, but Robert Ressler's complementary chronicle Whoever Fights Monsters – back in 2000, the discussion was always about tackling the serial-killer investigators' origin story via serialized storytelling. The filmmaker admits, however, "that I wasn't really watching TV at that point, so I didn't even know what I was looking for in a television show. I left it alone. Then around 2009, Charlize [Theron] gave me John's book, and I just blasted through it with a sort of true-crime fervor. It supported all my preconceptions about the guys [in that unit]."

"People will say, 'Oh, another serial killer thing.' But the men here are not John Doe from Seven. They aren't Bond villains. Most of them aren't living in hollowed-out volcanoes."-David Fincher

Still, the idea of working in television, even though the medium was already well into its modern Golden Age at that point, felt completely foreign to Fincher. It wasn't until he'd ventured into uncharted territory with Netflix and played a supervisory role on House of Cards – and thus helped usher in the streaming-service-as-Prestige-TV-provider era – that he started to sense the medium's possibilities. "Can you even call it television?" he asks. "I remember thinking, it's really this new hybrid, with these much more introspective and, to a certain extent, sinister characters who are given more leash and more space to tell you about themselves. So when Charlize came back and said 'Hey, now might be the time to do this,' I could see it.

"We began to kick around what intrigued us about John's narrative in the first place," he says. "Which was: How can you combat an antagonist that you have no understanding of? And how do you even begin to understand your enemy if you can't empathize with them in any way, shape or form?"

Both Fincher and Theron signed on as executive producers; she was the one who suggested Penhall, an England-born, Australia-raised playwright who'd penned the screenplay for The Road, to write and head up the series. ("He's a theater veteran, so he's not afraid of 10-page scenes of people talking – my kind of guy," Fincher jokes.) When they pitched the idea to Netflix, the director says that the reaction was not that the idea was too dark but rather, "'Oof, how do you make this not a network show?' Through some conversations and my own personal charisma" – Fincher clears his throat loudly for comic effect – "I explained to them that this wouldn't be the Charlie's Angels take of the scenario. Our show would be more meditative. And more odd."

Which was, not coincidentally, the same thing that attracted Groff and McCallany to the project. The Hamilton veteran was someone Fincher had had his eye on every since he met him during casting sessions for The Social Network; Groff had read for the Sean Parker role that ended up going to Justin Timberlake. "He was the one who got away," the director says. "We tried to find a place to fit him in there but couldn't." McCallany had first worked with the filmmaker on Alien 3 and immediately struck Fincher as someone who'd complement the younger performer without seeming, in his words, "like nothing but a wet blanket." And while both actors admit that the prospect of doing a Netflix show with Fincher was a no-brainer, neither of them were particularly gunning to be in a Prestige-TV version of CSI either. That idea was squashed immediately.

"I could tell this was going to be different from the second they handed me two five-page scenes to read in my audition," Groff says. "That's, ah, not usually the case. And when I talked to David, he described the show as being both a slow burn and a deep dive ... the idea being that, like a book, you can pick it up and put it down but it tells a story with a beginning, a middle and an end. It was immediately apparent that it would take its time, and that it's not just a psychological study of these killers. It's also a portrait of the way we try to manipulate them to talk to us."

"But please don't try this at home," McCallany jokes. "You could immediately tell that ok, this is going to be more cerebral. We could be the only show in the history of American television in which two guys play FBI agents and nobody ever yells, 'Stop, FBI!' David made it very clear, very early on to us that the incredibly witty, incredibly charming, super-intellectual serial killer – that's not the reality. The reality is that most of these guys are deeply fractured. Misanthropic. Tormented. Not all of them have genius-level IQs. So, you know be authentic rather than sensationalize."

"Ah yes, the supervillain serial killer!" Fincher says when the subject of famous screen multi-murderers comes up. He's well aware of the hold that someone like Hannibal Lecter has on the public imagination; the director is also all too aware of his own contribution to this mythology as well. "I feel like I'll spend the rest of my life apologizing for that," he sighs. "You know, people will obviously say, 'Oh, another serial killer thing,'" he admits. "But the men here are not John Doe from Seven. Even Zodiac isn't really about the Zodiac killer – it's about everyone else in that story.

"It's funny, we went to Quantico to meet the behavioral analysis team," he continues, "and at one point, we rounded a corner in the basement and there was this Madame Tussaud-style wax figure of Hannibal Lecter! The P.R. person told us, 'Oh yeah, our recruitment went way up after Silence of the Lambs, what did you think of that movie?" And I said, 'Mindhunter is the sort of the opposite of the serial killer as the gourmet opera fan bon vivant.' In reality, I think they’re incredibly real, incredibly human and incredibly bad. They are not Bond villains. Most of them are not living in hollowed-out volcanoes."

He pauses for a second. "So what did you think of our Ed Kemper?"

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The man dubbed the Co-ed Killer shows up in Mindhunter's second episode and is the first person to convince Ford and Tench that talking to these warped, disturbed men may bear fruit; it's not a spoiler to say that he also plays a larger part in this first season's overall arc, or to mention that Cameron Britton's singular take on the giant, damaged Kemper may be the breakthrough performance of the show. Fincher says that when he first saw the actor's tape, I remember saying to the casting director, "No one's allowed to talk to this guy, no one's allowed to rehearse with him, he's not to fraternize with anyone else in the cast.' We did one read-through and Cameron was like, 'Great, I'd love to come and…' And I just said 'We'll have you come in for a fitting to make sure the leg manacles fit, but I don't want this being informed by anything. You just have to came in from outer space and do this." And that's exactly what he did."

"Cameron had come in with research like crazy, and had a very specific idea of what he wanted to do with Kemper," Groff recalls. "I got to read with him once, and he just walked in, and started saying his lines in character, and ... ee had the voice, and everything. I had done the scenes in the audition, and I'm not a Method actor, but it was like 'Holy fucking shit!' To be sitting in this room with him in Los Angeles, all by myself, was terrifying."

"But his Kemper is still a recognizable human being," McCallany notes, "which goes right back to my story, and to David's point overall. The idea isn't to present these men as larger-than-life figures.

"We’re paying tribute to these guys who started what's become a cornerstone of what the FBI does now," Groff adds. "But like them, we’re also trying humanize the serial killer. Which, in some ways makes the whole thing even creepier and scarier."